Anaerobic
by The Goliath Beetle
Summary: Rin was oxygen. How do you breathe without oxygen? This is why Kakashi joined the ANBU. -Angsty KakaRin, rated for dark themes like self-harm-


_Anaerobic_

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He couldn't really point out the moment when Rin had become his oxygen. Maybe it was the security he felt when she smiled reassuringly at him, telling him his injuries were perfectly curable and not to worry about it. Maybe it was her gentle laughter at his slowly developing habit of arriving for appointments two hours late. Perhaps it was the understanding in her eyes when he cried in front of her, the Sharingan slowly rotating in an almost dreamlike way.

He couldn't really tell.

He barely remembered the first time they kissed. It was after a long, taxing mission and they'd gone to the bar and become well and truly drunk. One thing led to another and Kakashi found himself waking up beside her, naked, with only wisps of his memories to tell him what had transpired over the night. He'd spent fifteen minutes staring at her bare form, shocked, awed, disbelieving.

After that, one moment of passion started to merge with another. The hand-holding increased, the kissing became more meaningful. He could never utter the words that were always on the tip of his tongue, though he liked to think she knew. It simply wasn't Kakashi's style to tell her that he loved her. It wasn't how he did things. But he made sure his actions were loud and clear. Complimenting her, buying her those flowers, surprising her with a box of chocolates…he prayed all of that would get his message across.

Then she died.

Kakashi's hand went right through her, sparkling Chidori singing a victory song. He simply could not believe it. How…? When…? Why…? When he woke up, he was in a hospital with Minato-sensei looking at him with an expression he could not place.

(It was a mixture of sorrow, pity and concern, though all Kakashi could decipher was _rage _towards his only surviving student.)

Kakashi forgot how to eat.

He was slowly forgetting how to breathe, too.

He wouldn't interact with anyone, preferring to lock himself inside his one-bedroom flat. He would lie there on his bed with his Sharingan exposed. He would let the chakra drain out of him, feeling cleansed with the punishment. Sometimes, that wasn't enough. So he'd take a kunai and carve himself with it a bit. Pain was good. He deserved it.

That's how Minato-sensei found him one night. Sitting there, back against the room door, slowly stabbing himself in the thigh. It was _transcendent. _He was in a daze. A good thing. A daze meant he didn't have to think.

The blonde's voice was very serious, very calm when he said, "Kakashi, please put the kunai down."

Kakashi registered someone talking to him but chose to ignore it. Whatever they were saying couldn't possibly be more important than this. Whatever it was, it could wait.

Minato didn't repeat himself. He simply walked over to his student and in one fluid movement, disarmed him.

"Kakashi, look at me."

The boy met the elder's eyes, but at the same time, Kakashi was far, far away.

"Kakashi, _look at me._"

Minato finally shook him. Hard. He was expressionless as he saw his young charge snap out of whatever nightmare he was trapped in.

"You can't go on like this, Kakashi," he stated, his tone allowing no room for argument.

The silver-haired one remained silent. Kakashi just didn't care anymore.

After that incident, the boy stopped cutting. Instead, visiting the memorial stone became even more of a habit than before. He could literally remain there, motionless, for days. He didn't need food. He didn't need water. All he needed was oxygen. All he needed was Rin.

She was dead. And he was suffocating.

But you simply have to breathe to survive.

There was a stormy kind of darkness in Kakashi's heart. A depression. An agony. He couldn't function. Missions used to thrill him. Now, even the fiercest battles couldn't excite him. He used to have friends. These days he barely spoke to Asuma and Gai. Minato used to check on him from time to time, but as Hokage, the man had responsibilities too.

Kakashi was all alone.

There was a place meant especially for people like him.

The day his student got accepted into the ANBU, Minato got very, very drunk. Kushina made him pay for it, of course. But for once, Minato was numb to it.

"What's he doing?" he asked his wife. "Why did he join the…the…why the ANBU? Why does he hate himself so much?"

She had hugged him. "Kakashi is trying to bring normalcy back into his life."

"And joining the ANBU Black Ops is the way to do that?"

It was perfect.

You didn't have to think. You didn't have to feel. All you had to do was kill, and Kakashi was nothing if not a killer. (He'd demonstrated that perfectly when he struck a fist full of electricity through Rin's heart.) Behind the white porcelain mask, he could be anyone he wanted.

(He'd say the word _Wolf _aloud sometimes, relishing the feel of it on his tongue. Relishing how it had become his identity.)

The ANBU, ironically, kept him alive.

Because he knew for a fact that if he didn't kill someone else, he was going to kill himself. You see, his oxygen was gone. But he had to keep living. So he had learnt to breathe without air.

_Anaerobic respiration is usually practiced by microbes. The sort of creatures that feed off rotting carcasses. _

It made sense. The ANBU Black Ops were just like, well, microbes. They did all the dirty work, allowing the upper brass to take the credit. And Kakashi enjoyed being used and tossed aside, forgotten once his purpose had been served. He deserved it, after all.

Now every year, he plants a tree in her name. They're just babies, nothing more than tiny branches with small leaves. But oxygen cannot exist without them. Kakashi doesn't need air to survive now, he's learnt how to live without her.

But he likes to think that every year, there's just a little more oxygen to go around. It's nice to pretend that she's still there. It's nice to believe that she's still keeping him alive.

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**A/N: I write too much angst. Seriously. ****Anyway, I hope you liked it. Thanks for reading. Please review!**


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